Methods and compositions for treating or preventing, the occurrence of senile dementia of the Alzheimer's type, mild cognitive impairment, or other conditions arising from reduced neuronal metabolism and leading to lessened cognitive function are described. In a preferred embodiment the administration of triglycerides or fatty acids with chain lengths between 5 and 12, to said patient at a level to produce an improvement in cognitive ability, and a therapeutic agent selected from the group consisting of anti-Alzheimer's agents, anti-diabetic agents, agents capable of increasing utilization of lipids, anti-atherosclerotic agents, anti-hypertensive agents, anti-inflammatory agents, anti-obesity agents, and combinations thereof. Preferred therapeutic agents include donepezil, rivastigmine, galantamine, and memantine.